Brakes on my brain.... What brake booster should I use?

[dwbarnes]

I am slowly gaining all the parts I need to do a five lug, four wheel disc conversion on my '85 T top. I am going to be running brakes off a '01 Cobra on all four corners. The '01 Cobra front calipers have a 40.5mm piston compared to the smaller 38mm pistons found on earlier Cobras. I know there are clearance issues for us four-eye owners, and I would really like to avoid taking a hammer to my strut tower to make everything fit. I have heard of guys using '93 Cobra/'94-'95 GT boosters, '94-'96 Cobra boosters, and Fairmont boosters. What brake booster and master cylinder would work best for my set up? Thanks for the help!

[wraithracing]

Before re-inventing the wheel, I would recommend using your stock setup if it is in good working shape. The stock Fox booster can/will work just fine with 4 wheel disc conversions. There is no immediate need to make a change unless your booster is inoperable.

The same can be said for the stock M/C. If your's is in good working condition, you might want to see how the brake pedal feels with the stock M/C and then adjust from there if needed. The stock M/C is a 21mm bore (@ 7/8") so that is very similar is size to the 94/95 Cobra 15/16 M/C.

Unless you need to replace bad parts, I would save the initial $$ and get the swap completed and adjust from there as needed. Good Luck!

[dwbarnes]

Thanks Trey! When I brought the car home the brakes were terrible. I put it on the lift and changed some bad lines, put on a new set of pads, turned the rotors, and flushed the old brake fluid. It made a considerable difference in the braking, but its still not where I feel it should be. This leads me to believe it might just be better to go ahead and change the booster and MC.

[wraithracing]

That's understandable, but the question is are the booster and M/C bad or is the poor braking due to the poor pads, hardware, etc.? I am all for replacing bad parts with quality parts, but no sense in spending $$ on parts that are not needed.

Do you have power assist when applying the brakes? Does the booster hiss or leak vacuum when applying the brakes? Is your pedal rock hard?

Do the brakes function? Have you flushed and bleed the entire system with quality Dot 3 Brake Fluid? Are all the rubber lines in good condition? Are the pads and shoes in good condition? Are the rear shoes adjusted properly? All of these items can lead to poor or insufficient brake performance. Unfortunately most Mcparts stores pads and shoes are ok at best in regards to good performance. Buy the cheap stuff and it's even worse. I am no proponent of the OEM brakes on a Fox as I swap virtually all of mine out for SN95 or better, so I understand your issues. Just trying to help you determine if your current booster and M/C are functioning or need to be replaced.

[OX1]

There is always hydroboost. No fitment issues and
more force to MC than any vac booster.

[dwbarnes]

There is no hiss or leak when I apply the brakes. My biggest complaint is the brake pedal just feels soft. The car stops, not on a dime by any means, but better than it did when I brought it home. I did replace the soft lines up front, as they looked and felt brittle. I also replaced the vacuum line going to the booster. The pads I used were the store brand, but not their economy pads either. When I flushed the system, I replaced the fluid with Motorcraft Dot 3 fluid. Do you think the problem is in the M/C?

[dwbarnes]

There is always hydroboost. No fitment issues and
more force to MC than any vac booster.

What is your hydroboost set up out of?

[wraithracing]

Soft pedal is generally a sign of air in the system.

I would highly recommend bleeding the entire system again, making sure that you have clean fresh fluid coming out at every wheel before you stop bleeding that corner.

Sounds like your Booster and M/C are working. I would try the bleeding before moving forward with any additional repairs or part replacements.

Hydroboost is an excellent option, but is not a simple bolt in without some modifications. The Hydro boost can be a benefit if you have an engine that doesn't make a lot of vacuum to run a booster properly. I would still run a standard booster otherwise IMHO.

[erratic50]

M1858 with 1 line adapter. 1" bore, works perfectly with the fox booster.

Im using it with SN95 brakes. Stock rear, 11" 99-04GT front.

A good friend runs 13" 03 cobras in front with SN95 rear. Also works perfectly with this master cyl

[OX1]

What is your hydroboost set up out of?

99-04 GT stang (96 up cobra also I believe).
Like this one.

https://www.ebay.com/itm/1999-2004-M...4383.l4275.c10

Here are some more pics if interested

http://luxjo.supermotors.net/DADSLTD/HYDROBOOST/

and even more, although this is the same HB installed in a 70 bronco

http://luxjo.supermotors.net/70%20EB...%20HYDROBOOST/

[OX1]

The Hydro boost can be a benefit if you have an engine that doesn't make a lot of vacuum to run a booster properly. I would still run a standard booster otherwise IMHO.

It can also "fix" long mushy pedal travel and/or short action firm pedal (but not much braking action)
brake setups (when everything else you have tried fails). For whatever reason, my dads LTD fell into
this category. It was very odd as booster, MC, and calipers sizes were almost identical to my Capri
(which was converted to 11" front disk, rear FMS 4 lug disk, and upgraded MC). The Capri
brakes I thought were pretty good, so why shouldn't the LTD brakes be just as good
(LTD had been converted to all MK VII brakes, except electric HB).

I do prefer virtually zero pedal travel brakes and low pedal actuation force.
Usually an impossible combo to get except with larger MC's AND the largest
of vac boosters (much larger than will fit in a fox).

Some complain that the way I like brakes, is too touchy. Being a lighter guy,
I don't have that complaint. I find it much easier to modulate brakes,
when overall pedal travel is very short and light.

[erratic50]

My suggestion is $20.

[erratic50]

Too little pedal movement / over reacting brakes:
- master cyl bore is too large relative to the calipers
- misadjusted/broken/stuck proportioning valve

Too much effort:
- weak booster
- master cyl bore too large
- bent or misadjusted booster to master cyl rod
- low vacuum

Too much pedal movement or goes to floor
- fluid leak
- bad master cyl
- air in system
- slightly sticking caliper boiling brake fluid
- brakes overheating
- too small master cyl
- misadjusted booster to master cyl rod

1" bore M1858 with fox booster works perfectly with 99GT or 2003 cobra front calipers, and 95GT rear.

Great pedal actuation, expected pedal effort to lockup

It's my understanding that 60mm front 38mm rear four lug al

As for the rest of it, save your money!

[OX1]

My suggestion is $20.

No argument for most to try other things before HB, unless
you prefer very short travel and light engagement.

Even my new fusion sport, which has excellent brakes,
has a shorter pedal stroke after the second pump. I drove
6 of them before buying mine, they all do it.

Even my 14 Stang GT does this, even worse than the fusion.
I loath brakes that have a substantially shorter pedal stroke
after first pump. HB brakes never do that.

My 15 fusion and 03 EVO8 were the only cars I can recall
that did not that at all. I have heard brembos on a stock base newer
GT (14ish timeframe) also leaves many feeling like brakes are too touchy,
hence why GT500 booster is actually smaller than stock GT on 11-14's.

[OX1]

Added this stuff here, as no one will find that other thread 2 years from now


I used a late 70 lincoln saginaw pump with dual return
(has two low pressure return fittings on pump reservior,
one from HB, and one from steering rack)
.
PS pump bracket I used was from wildhorses
(needs some grinding to use Lincoln pump above)

https://www.wildhorses4x4.com/produc...Steering_Pumps

Need adapter brass plugs to allow to use of AN fittings
for pressure lines on HB. (have to dig up receipt of where
I got them)

http://luxjo.supermotors.net/70%20EB...T/DCP02906.JPG
http://luxjo.supermotors.net/70%20EB...T/DCP02905.JPG
http://luxjo.supermotors.net/70%20EB...T/DCP02907.JPG

I think it was 3 out of 4 holes lined up to mount HB,
but it's been many years since that was installed
on a fox.

Will need to tap and thread rod for pedal connection.
http://luxjo.supermotors.net/70%20EB...T/DCP02903.JPG
(that pic shows long rod needed for 70 classic bronco,
fox is shorter)

Otherwise pretty straightforward, can look up
general plumbing for hydroboost installs if needed,
they all plumb pretty much the same for high and
low pressure hoses.

I bought used HB/MC, and comb valve all in one shot.
http://luxjo.supermotors.net/70%20EB...T/DCP02863.JPG

But I used stock prop valve on ltd, gutting rear prop part.

http://luxjo.supermotors.net/DADSLTD...T/DCP04963.JPG

and using adj propr valve for rear.

http://luxjo.supermotors.net/DADSLTD...E/IMG_1048.JPG

[dwbarnes]

M1858 with 1 line adapter. 1" bore, works perfectly with the fox booster.

Im using it with SN95 brakes. Stock rear, 11" 99-04GT front.

A good friend runs 13" 03 cobras in front with SN95 rear. Also works perfectly with this master cyl

Will a master cylinder off a '93 Cobra do the same thing? I am almost certain is has a 1" bore as well.

[Lowetlx]

yes the 93 cobra is also 1”. But it has metric threaded ports. It Would require more adapters/ line fabrication than the one erratic mentioned. The one he mentioned needs an adapter to go from 3/8”x24 to 7/16x24 double flare on the front port. Or you can cut and reflare that line with a 7/16 tube nut. Also the 93 has the plastic reservoir. The other has the stock look to it being all cast.

[erratic50]

Exactly! The one I mentioned is a much easier swap. Also I'll take metal over plastic any day.

Think about the melting points when you are on lap who knows around town on a busy day and your DOT4 is absolutely boiling when a caliper just barely hangs up like the 99-04GT calipers are prone to doing. The metal provides better cooling properties. And the plastic tank would have melted......

The Mcparts stores usually carry the required line. I went adapter because the line was out of stock.

There a bunch of other dorking around with lines needed to make the Cobra MC work. M1858 is a slam dunk.

[Jack Hidley]

No adapters. No messing around with brakes lines. Straight bolt in for the car in question.

http://www.maximummotorsports.com/Ma...ang-P1382.aspx

I would never use a m/c with a metal reservoir. With a plastic reservoir, you can see both the level of the fluid and how dirty it is. With a metal reservoir this is impossible without taking a sample of the fluid out. The m/c with a plastic reservoir is much lighter. I've worked on and seen hundreds of Mustang track and road race cars. Cars that are WOT for 70% of the lap for 40 minutes straight. I've never seen one with a melted OEM m/c that has a plastic reservoir.

[svtrichie]

This whole thread is funny. It's like the first time anyone had ever upgraded 4 lug brakes!

[dwbarnes]

This whole thread is funny. It's like the first time anyone had ever upgraded 4 lug brakes!

Well, this just happens to be the first time I’ve done a five lug, four wheel disc conversion. That’s why I’m asking for advice from members that have done this before. I’m glad it’s entertaining for you.

[dwbarnes]

No adapters. No messing around with brakes lines. Straight bolt in for the car in question.

http://www.maximummotorsports.com/Ma...ang-P1382.aspx

I would never use a m/c with a metal reservoir. With a plastic reservoir, you can see both the level of the fluid and how dirty it is. With a metal reservoir this is impossible without taking a sample of the fluid out. The m/c with a plastic reservoir is much lighter. I've worked on and seen hundreds of Mustang track and road race cars. Cars that are WOT for 70% of the lap for 40 minutes straight. I've never seen one with a melted OEM m/c that has a plastic reservoir.

Thanks for the link! I think this is the route I’m going to go.